On the A320/1, the hydraulics to the gear are inhibited above 250 knots. So even if the lever is selected down nothing will (should
) happen.
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Yes there would be forms to fill in but that would probably be to do with trying to locate the gear doors which would more than likely detach if the gear extended in the cruise. Of course the other big worry there is what damage they would do as they departed (and landed).
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I've always understood gear extention to be freefall, but damped but the fluid in the retraction cylinders. The only pressure applied is to the overcentre lock to lock the gear in place.
A4